ZAP Conducts IRS Program in the Dominican Republic

ZAP pilots IRS in the DR to reduce spread of the Zika virus

The USAID-funded Zika AIRS Project in the Dominican Republic recently conducted an indoor residual spraying (IRS) campaign to reduce the spread of the Zika virus. IRS is not new in the Dominican Republic, having been used to control malaria outbreaks in the past. However, use of IRS to control for Aedes aegypti, the vector that spreads the Zika virus, encompasses a slightly different methodology due to resting behaviors of recently-fed female mosquitoes. Once they bite, female Aedes aegypti seek a resting place in the lower walls of a dwelling or in dark spaces, such as in closets or underneath furniture. To target the mosquitoes, ZAP sprayed walls up to 1.5m above ground and under furniture, rather than on all wall surfaces and ceilings as is usually done for malaria control.

ZAP Technicians sprayed 11,706 homes in peri-urban areas in the Dominican Republic, protecting more than 38,000 people. Photo: Emily MacDonald

With approval from the Ministry of Health (MOH), ZAP procured spray equipment, personal protective equipment, insecticide and other supplies; hired and trained seasonal workers; established an operations center and soak pits; and provided technical support for the IRS campaign. In consultations with the MOH, 18 neighborhoods around the city of San Cristobal were chosen for the intervention. Thirteen neighborhoods were selected due to elevated prevalence of Zika during the 2016 outbreak and high mosquito infestation rates as established by recent entomological surveys.

Between June 12 and July 4, 2017, ZAP sprayed 11,706 homes in peri-urban areas of San Cristobal, protecting 38,378 people. Hixbonny Perez, a ZAP team leader, sprayed his own neighborhood. According to his neighbor, despite some rains, there were no mosquitoes inside. His home had been full of mosquitoes and other insects beforehand. Similar accounts were provided by other residents whose houses were sprayed. They agreed that the insecticide was “good” because it killed all kinds of bugs around the house.

Likewise, when Ing Angel Solis, senior entomologist at the National Center for the Control of Tropical Diseases, visited the IRS sites he was quite pleased with the overall organization and implementation of the campaign. He acknowledged the benefits of the campaign in a high infestation area.

Entomological monitoring of the IRS pilot sites will continue until November 2017, with monthly collections of adult mosquito samples and other measurements to assess several study parameters, including residual efficacy and mosquito infestation levels.